Updates handling of go test flags -run and -bench to give alternation
precendence over the / delimiter. Currently, `A/B|C/D` is effectively
`A/(B|C)/D` - with this change, it changes to effectively `(A/B)|(C/D)`.
Fixes #39904
Change-Id: Iebe5efd8d91c72eed6351bd63b4689b0fcb0ed0f
Reviewed-on: https://go-review.googlesource.com/c/go/+/343883
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Than McIntosh <thanm@google.com>